This invention relates to the removal of phenols, unavoidably produced as byproducts in the underground gasification of coal, by treatment of the groundwater after gasification.
Somewhat related to this invention is the treatment of hydrocarbon streams for the removal of phenol therefrom as shown in Schlosberg, et al., U.S. Pat. No. 4,256,568 (1981). In this patent, hydrocarbon streams are treated with multivalent metal compositions (hydroxides) to convert phenols to the corresponding phenates. In the Specification of this patent, a distinction is made for this treatment between the multivalent hydroxides and monovalent hydroxides such as sodium or potassium hydroxide. The patent shows the formation of a salt by the reaction of the phenol with sodium hydroxide.
The present invention is distinguished from that of the patent mentioned since the treatment is carried out in the formation. Further, systems are described for the destruction of the undesirable phenols.
During the underground gasification of coal phenols are produced as stated above. These phenols are environmentally hazardous because they are toxic and are soluble in groundwater. Years after gasification of a coal seam, phenol concentrations in the groundwater near the gasification sites have been unacceptably high.
An object of this invention is to provide a method for the removal of phenols from underground formations after coal gasification. Other objects and advantages of the invention will be apparent to those skilled in the art upon reading this disclosure.
The term "phenols" is used herein to include the various hydroxybenzenes, including phenol itself, catechol, resorcinol, hydroquinone, pyrogallol, hydroxyquinol, and phloroglucinol. The present invention will also serve to remove any thiophenols present, but these are present in far lesser quantities than the phenols themselves.